Polyhydroxy aromatic coating compositions for reinforcing glass fibers used in cementitious products

Abstract

A composition for coating glass fibers intended for use as reinforcement in cementitious products, containing, as a protective material, at least one monocyclic or polycyclic aromatic compound which has at least three hydroxyl groups on the aromatic ring or (in a polycyclic compound) on at least one of the aromatic rings, said composition, when applied to a strand of glass fibres which is subsequently encased in a block of ordinary Portland cement paste which is allowed to cure and kept for 28 days at 50° C, producing an improvement of at least 10% in the tensile strength of the strand as compared with that of a strand similarly treated and tested but without application of said composition. Preferably, the aromatic compound is soluble in a calcium hydroxide solution. A preferred compound is pyrogallol.

I claim: 
     
       1. Glass fibres for use as reinforcement in cementitious products, said fibres being coated with a composition which consists essentially of a protective material to reduce deterioration of the glass fibres, said protective material being non-polymeric, a monocyclic or polycyclic aromatic compound which has at least three hydroxyl groups on the aromatic ring or when a polycyclic compound is employed, on at least one of the aromatic rings. 
     
     
       2. Glass fibres according to claim 1, said fibres being formed from an alkali-resistant glass containing at least 5 mol % ZrO 2 . 
     
     
       3. Glass fibres according to claim 1, wherein the aromatic compound is soluble in a calcium hydroxide solution. 
     
     
       4. Glass fibres according to claim 1, wherein the aromatic compound is a monocyclic 6-membered-ring compound having at least three hydroxyl groups substituted in the ring. 
     
     
       5. Glass fibres according to claim 3, wherein the aromatic compound is pyrogallol. 
     
     
       6. Glass fibres according to claim 4, wherein the aromatic compound is hydroxy hydroquinone. 
     
     
       7. Glass fibres according to claim 4, wherein the aromatic compound is phloroglucinol. 
     
     
       8. Glass fibres according to claim 1, wherein the aromatic compound is a product obtained by oxidation in alkaline solution of a monocyclic 6-membered-ring compound having at least three hydroxyl groups substituted in the ring. 
     
     
       9. Glass fibres according to claim 8, wherein the aromatic compound is an ammonium oxidation salt of pyrogallol. 
     
     
       10. Glass fibres according to claim 1, wherein the aromatic compound is a monocyclic 6-membered-ring compound having at least three hydroxyl groups and at least one other group substituted in the ring, or a carboxylic acid salt or ester thereon. 
     
     
       11. Glass fibres according to claim 10, wherein the aromatic compound is 2, 3, 4 tri-hydroxybenzoic acid. 
     
     
       12. Glass fibres according to claim 10, wherein the aromatic compound is 3, 4, 5 tri-hydroxybenzoic acid. 
     
     
       13. Glass fibres according to claim 10, wherein the aromatic compound is propyl gallate. 
     
     
       14. Glass fibres according to claim 10, wherein the aromatic compound is 2, 4, 6 tri-hydroxybenzoic acid. 
     
     
       15. Glass fibres according to claim 10, wherein the aromatic compound is 2, 4, 6 tri-hydroxybenzaldehyde. 
     
     
       16. Glass fibres according to claim 10, wherein the aromatic compound is 2, 3, 4 tri-hydroxyacetophenone. 
     
     
       17. Glass fibres according to claim 10, wherein the aromatic compound is 2, 4, 6 tri-hydroxyacetophenone. 
     
     
       18. Glass fibres according to claim 10, wherein the aromatic compound is tetrahydroxy-p-quinone dihydrate. 
     
     
       19. Glass fibres according to claim 1, wherein the aromatic compound is a product obtained by oxidation in alkaline solution of a monocyclic 6-membered-ring compound having at least three hydroxyl groups and at least one other group substituted in the ring. 
     
     
       20. Glass fibres according to claim 19, wherein the aromatic compound is an ammonium oxidation salt of gallic acid. 
     
     
       21. Glass fibres according to claim 1, wherein the aromatic compound is a hetero-monocyclic 6-membered-ring aromatic compound having two nitrogen atoms within the ring and at least three hydroxyl groups are substituents in the ring. 
     
     
       22. Glass fibres according to claim 21, wherein the aromatic compound is 2, 4, 6 tri-hydroxypyrimidine. 
     
     
       23. Glass fibres according to claim 1, wherein the aromatic compound is a polycyclic aromatic hydrocarbon having at least three hydroxyl groups substituted in a single 6-membered ring. 
     
     
       24. Glass fibres according to claim 23, wherein the aromatic compound is purpurogallin. 
     
     
       25. Glass fibres according to claim 23, wherein the aromatic compound is 1, 2, 4 tri-hydroxyanthraquinone. 
     
     
       26. Glass fibres according to claim 23, wherein the aromatic compound is 2, 4, 6 tri-hydroxy benzophenone. 
     
     
       27. Glass fibres according to claim 23, wherein the aromatic compound is tannic acid. 
     
     
       28. Glass fibres according to claim 23, wherein the aromatic compound is a naturally occurring vegetable tannin. 
     
     
       29. Glass fibres for use as reinforcement in cementitious products, said fibres being coated with a composition which consists essentially of a protective material to reduce deterioration of the glass fibres, said protective material being a non-polymeric, monocyclic of polycyclic aromatic compound which has at least three hydroxyl groups on the aromatic ring or when a polycyclic compound is employed, on at least one of the aromatic rings together with a film-forming agent and a linking agent. 
     
     
       30. Glass fibres according to claim 29, wherein the film-forming agent comprises a polyvinyl acetate of cationic character. 
     
     
       31. Glass fibres according to claim 29, wherein the film-forming agent comprises a polyethylene glycol of non-ionic character. 
     
     
       32. Glass fibres according to claim 29, wherein the linking agent is a silane. 
     
     
       33. Glass fibres according to claim 2, said glass fibres having a further protective coating applied after the glass fibres have been coated with said composition. 
     
     
       34. Glass fibres according to claim 33, wherein said further protective coating is an epoxy resin polymer.